Eonycteris majorgreater dawn bat

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Geographic Range

The distribution of Eonycteris major includes the Philippines through Borneo. In Borneo, there are scattered records from most areas including Kota Kinabalu and Ranau in Sabah. It is also found in Gunung Dulit and Kuching in Sarawak, Kutai in East Kalimantan, and upper Sungai Tengah in South Kalimantan. The only area it is not found is in Central and West Kalimantan. In the Philiippines, the distribution includes Biliran, Leyte, Lubang, Luzon, Maripipi, Mindanao, Negros, and Siargao. (Mickleburgh, et al., 1992)

Habitat

The roosting habitat of E. major usually includes caves and hollow trees. The subspecies E. m. robusta may be dependent upon primary forest as well as caves and has been taken from near sea level to 1100m. (Mickleburgh, et al., 1992; Nowak, 1994)

  • Other Habitat Features
  • caves
  • Range elevation
    0 to 1100 m
    0.00 to 3608.92 ft

Physical Description

The fur of E. major is identified as uniform and dark, blackish brown. Like most other fruit bats of this genus, the muzzle is long, slender, and slightly decurved. The tongue is also very long and slender, and protrudes from the mouth. Both characteristics help to pick up nectar and pollen, the main source of food. The cheek teeth are reduced in size. Overall, the bats from the subfamily Pteropodidae are characterized by long, needle-like canines, which are strongly curved outwards in the lower jaw. The upper incisors are small and they project forward slightly and are separated from each other by small gaps. The dental formula is unknown but the dental formula for most Pteropodidae is 2/2, 1/1, 3/3, 2/3. The tail is usually very short, averaging 18 mm, and the ear length averages 21 mm. The forearm (length outside of the elbow to the outside of wrist in a bent wing) averages from 71 mm to 80 mm. Another distinguishing characteristic is the lack of a claw on the second digit of the wing, which is usually present in Pteropodidae. Although there is no information about sexual dimorphism, the closest relative of E. major is E. spelaea, which is known to be sexually dimorphic; males are generally larger than females. (Nowak, 1994; Payne and Francis, 1985)

  • Average mass
    91 g
    3.21 oz

Reproduction

There is little available information on mating systems in Eonycteris major.

There is no information about reproductive behavior in E. major but there is some information on its closest relative, E. spelaea. The females have been found to be polyestrous and pregnancies that begin during later stages of lactation are successive. The gestation period is a little bit longer than six months but can be as long as 200 days. Generally females have one young per litter, and rarely two. The young are attached to the nipple for about 4 to 6 weeks and weaning occurs after 3 months. They reach sexual maturity after one year in females and after two years in males. ("Animal Diversity Web", 2004; Nowak, 1994)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • viviparous
  • Breeding interval
    There is little information, but in their relative E. spelaea, the breeding happens year round and peaks throughout the year.

There is little available information on the parental investment of E. major, but observations of their relative E. spelaea show that the young take hold of a nipple shortly after parturition. For 4 to 6 weeks, the young stay firmly attached as the female flies around. The young can make short flights on their own after 4 to 6 weeks and weaning occurs three months later. (Nowak, 1994)

  • Parental Investment
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

There is little available information on studies of the lifespan of this species either in the wild or in captivity.

Behavior

The subspecies E. m. robusta is known to be gregarious. Several hundred were found roosting in colonies that were divided into groups, separated by sex. They are also known to share roosting caves with E. spelaea and probably Rousettus amplexicaudatus. (Mickleburgh, et al., 1992; Nowak, 1994)

Home Range

There is little available information on the home range of E. major. The nearest relative, E. spelaea, migrates long distances to its feeding grounds and in general, members of the family Pteropodidae are known to make long flights between their roosting and feeding areas. (Altringham, 1996; Nowak, 1994)

Communication and Perception

There is little available information on the way this species communicates how it perceives the environment. In general, members of the family Pteropodidae have large, well-developed eyes, and therefore perceive their environment visually. Most species of this family are also known to locate their food by smell. (Nowak, 1994; Nowak, 1994)

  • Communication Channels
  • visual

Food Habits

Not much is known about the specific plants E. major feeds on, but it is known that its natural foods appear to be mainly made up of pollen and nectar. (Mickleburgh, et al., 1992; Nowak, 1994)

  • Plant Foods
  • fruit
  • nectar
  • pollen

Predation

There is little available information on the predators of this species or the adaptations it has to avoid such predators.

Ecosystem Roles

They serve a role in the pollination of their host plants.

  • Ecosystem Impact
  • pollinates

Economic Importance for Humans: Positive

There is little available information on the benefits of this species to humans except as a pollinator.

Economic Importance for Humans: Negative

There are no known adverse effects of E. major on humans.

Conservation Status

This species is not threatened and there is no evidence of serious threats to the population. On the other hand, its subspecies E. m. robusta is identified as rare. It is believed that this rarity may have been caused by deforestation, because E. major is strongly association with primary forests. This species may be threatened but it is difficult to know because it is so rare. It is believed that even without protection, they will continue to survive with low numbers as long as there are undisturbed cave roosts available. (Mickleburgh, et al., 1992)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Yan-Iuan Ho (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nectarivore

an animal that mainly eats nectar from flowers

nocturnal

active during the night

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

2004. "Animal Diversity Web" (On-line). Accessed February 11, 2004 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Eonycteris_spelaea.html.

Altringham, J. 1996. Bats Biology and Behaviour. United States: Oxford University Press.

Mickleburgh, S., A. Hutson, P. Racey. 1992. Old World Fruit Bats. Gland, Switzerland: IUCN.

Nowak, R. 1994. Walker's Bats of the World. Baltimore and London: The Johns Hopkins University Press.

Payne, J., C. Francis. 1985. A Field Guide to the Mammals of Borneo. Kuala Lumpur: The Sabah Society.